Mobile devices like cellular telephones and personal digital assistants continue to grow in power and capabilities. As the bandwidth for such devices grows, the applications that are made available on mobile devices also expand and mature. For example, e-mail is now a common application on mobile devices, as is text messaging. In addition, with improved graphical interfaces, mobile device owners can use their devices to buy products and services on-line. For example, many people purchase video games, ring tones, or music for use on their cellular telephones. In addition, people can purchase other products, such as food, gifts, and other items, such as by using WAP, SMS, or other protocols.
In general, on-line purchases require the identification, in some manner, of the purchaser. The identification may be of the actual purchaser, or of an account associated with the purchaser. Various mechanisms may be used to make a transaction more or less anonymous also. However, mobile devices are typically controlled by a particular operator, or carrier, such as Sprint, AT&T, Verizon, NextTel and others, that tend to mask the identity of devices to some extent. Specifically, each operator may have particular protocols and other standards for sharing information with its subscribers and with third parties outside its network, such as through wireless access protocol (WAP) gateways. Such operational variability can make it difficult to obtain information about various mobile network subscribers, and may make it particularly difficult to obtain identifying information that will permit a third party to bill a mobile network subscriber. In addition, it may be desirable to prevent fraud in mobile transactions, such as by spoofing or identity theft.